Improper Link Resolution Before File Access ('Link Following')
passwd in Directory Services in Mac OS X 10.3.x before 10.3.9 and 10.4.x before 10.4.5 allows local users to overwrite arbitrary files via a symlink attack on the .pwtmp.[PID] temporary file.
CWE-59 - Improper Link Resolution Before File Access
'Improper link resolution before file access' occurs when software accesses a file resource but fails to verify that the file isn't a link or shortcut to another file. An attacker can potentially gain access to arbitrary files and from there the impact can vary, depending on the application, from sensitive data exposure to remote code execution.